Animation slider (driver?)
For a compact "control thing" you can use the dope sheet view. This will combine all object's animation data into one window for editing. In the dope sheet view you can reverse the animation data (for the door to reopen after closing) and then simply duplicate this new set of keyframes and voila 4 cycles of the door animation. Then again, it depends on what you are wanting to use this longer animation for, nevertheless, here is an excellent tutorial explaining the dope sheet: https://www.youtube.com/watch?v=JIWd0xfzxIc